Как сельдь в бочке (Kak sel'd' v bochke)

Literally: Like herrings in a barrel

Example: “В утреннем автобусе мы стояли как сельди в бочке.” — On the morning bus we were packed like sardines.

English equivalent: Packed like sardines

Origin: Herring was salted and packed into barrels so tightly that the fish lay pressed together without a gap, and herring barrels were a common sight in Russian shops and markets. Michelson's 19th-century phrase dictionary records the comparison from the writer Pyotr Boborykin and from the surgeon Nikolai Pirogov's letters to his wife from besieged Sevastopol (1854–55), where the wounded are crammed in "like herrings in a keg." English packs people like sardines.